In the past decade functional neuroimaging has been extremely successful in establishing functional segregation as a principle of organisation in the human brain. The nature of the functional specialisation is attributed to the sensori-motor or cognitive process that has been manipulated experimentally. Newer approaches have introduced a number of concepts into neuroimaging. An experiment that studies the effect of attention on visual pathways is described. The analysis reveals a change in the connectivity of two cortical areas involved in visual motion analysis. A nonlinear modulation of this connectivity by the prefrontal regions is shown.